Manufacture of artificial materials



Patented May 25, 1937 UNITED STATES PATENT OFFICE MANUFACTURE or ARTIFTCIAL MATERIALS No Drawing. Application April 26, 1932, Serial No. 607,668. In Great Britain June 23, 1931 13 Claims.

This invention relates to the manufacture of artificial filaments, threads, films and other products by wet spinning processes from solutions of organic derivatives of cellulose, for example cellulose acetate, formate, propionate, or butyrate, or methyl, ethyl or benzyl cellulose, and is a continuation in part of the invention of U. S. application S. No. 402,785 filed October 26th, 1929.

U. S. application S. No. 402,785 describes processes wherein materials of the above type are produced by wet spinning processes in which coagulation is effected in the presence of relatively strong solvents or swelling agents for the cellulose derivative. The solvent or swelling agent may be present in such proportion that the materials emerge from the coagulation medium in a plastic condition. As example of solvents or swelling agents which may be employed in the process mention is made of diacetone alcohol, diethyl tartrate, mono-and di-acetin, and ethyl lactate. We have now found that the process of U. S. application S. No. 402,785 may very advantageously be carried out by employing spinning baths containing a lower aliphatic acid, for example acetic acid .or formic acid, preferably in the presence of a relatively high boiling solvent for the cellulose derivative, for example ethyl lactate.

According therefore to the present invention artificial filaments, threads, ribbons, andthelike products are produced by spinning solutions of cellulose acetate or other esters or ethers of cellulose into a coagulating medium containing a relatively high concentration of a solvent or swelling agent comprising a lower aliphatic acid, preferably together with a relatively high boiling solvent for the cellulose derivative such for example as ethyl lactate.

Excellent results are obtained using baths containing the lower aliphatic acid in a proportion ranging from.20% to 50% or even higher. When a relatively high boiling solvent such as ethyl lactate is contained in the bath the proportion in which the acid is present may be varied according to the amount of such other solvent present in the coagulating medium. Where for example the bath contains some 20% of ethyl lactate good results are obtained ithconcentrations of acetic acid of the order of 30%. On the other hand with a bath containing smaller concentrations, for example 10%orless of the high boiling solvent or baths from which such solventis absent the acid maybe employed in higher concentrations for exampleup to 40%.

It is of advantage to employ in the coagulating medium soluble salts or other substances capable of reducing the solubility, in the water or other non-solvent constituent of said medium, of the aliphatic acid and/or other solvent present there- 5 in. The best results in fact appear to be obtained when such substances are present. Thus for example by spinning solutions of cellulose acetate in acetone into a bath containing 30% acetic acid, 20% ethyl lactate and 10% sodium acetate strong lustrous filaments of excellent quality are obtainable. If approximately 10% of sodium acetate is present it is possible to employ the acid as sole solvent in concentrations of from 50% to 55%. Among other substances capable of decreasing the solubility of the aliphatic acid and/or other solvents, in the nonsolvent medium, mention may be made of soluble salts in general, and of sugars or other polyhydric alcohols. By varying the amount of such substances in the coagulating medium, the lustre of the products may very conveniently be controlled. Thus in general increase in the amount in which such substances are-employed results in products of enhanced lustre. When, on the other hand, products of subdued lustre are required, relatively large proportions of acid may be employed in the presence of small proportions of salts or the like. 30

As mentioned above we prefer to employ in the coagulating medium, besides acetic acid, formic acid, or other lower aliphatic acid, a relatively high boiling solvent forthe cellulose derivative. to afford the best results. Other solvents may however be employed alternatively or in addition to the ethyl lactate. Among such solvents mention may be made of diacetone alcohol, diethyl tartrate, monoand di-acetin, and the solvents 4 referred to in. British Patent No. 378,858, namely such solvents as glycol mono-acetate glycol diacetate, methyl glycol mono-acetate and other esters especially mono-carboxylic'esters of glycol and its alkyl substitution products. vents or swelling agents of low boiling point, e. g. acetone, acetaldehyde, formaldehyde, or alcohol may ifdesired be contained in the coagulating medium. The coagulating medium may in fact contain any solvent, latent' solvent, swelling,

agent, or plasticizer, with or without the addition of any substance or substances capable of decreasing the solubility of. such agents in the nonsolvent medium, provided 'of course that the various constituentsemployed are compatible one 5.5,

Of such solvents ethyl lactate appears 35:

Again, sol- 4 5 with another and with the other constituents of the coagulating medium.

Any suitable non-solvent for the cellulose derivative may be employed in the coagulating medium. We prefer to employ Water as the nonsolvent, but other substances which are solvents for at least one major constituent of the spinning solution and non-solvents for the cellulose derivative are not excluded. Among such substances benzene, toluene, and other liquid hydrocarbons may be referred to.

The spinning solution may contain any suitable solvent, simple or mixed, for the cellulose derivative. We prefer to employ solutions of cellulose acetate in acetone. The spinning solution may contain swelling agents, for example ethyl alcohol and other lower hydroxy alcohols, and/or non-solvents, for example benzene, toluene, and other liquid hydrocarbons, olive oil, castor oil or other oils of natural origin, for the cellulose derivative. The solvent itself may be a solvent mixture, for example a mixture comprising one or more relatively polar liquids such as ethyl or methyl alcohol, with one or more relatively non-polar liquids such as ethylene dichloride and methylene dichloride. The spinning solution should not contain large proportions of non-solvents which are insufficiently soluble in the coagulating media to be removed during the spinning process, nor of course should non-solvents be present in a proportion suflicient to precipitate the cellulose derivative from solution. The proportions may however be such that the cellulose derivative is near the precipitation point. Where a solvent compatible with water is employed, such for example as acetone the spinning solution may with advantage contain a proportion of water determined in accordance with the solubility characteristics of 40 the particular cellulose derivative. The spinning solution may moreover contain relatively high boiling solvents for the cellulose derivative, for example any of those referred to above as optional constituents of the coagulating medium. Spinning may be effected so that at least a part of any high boiling solvents or non-solvents,

present in the spinning solution is retained in the material.

Any solvents retained in or upon the filaments or other materials after emergence from the coagulating medium may if desired be removed from the materials by any suitable means, for example by washing with water or other suitable agent, by passing the materials through a heated atmosphere or over a heated surface, or by treatment in a hydro-extractor or other centrifugal device, or simply by means of an airrun. In removing such agents by a washing process it is preferable to employ a series of wash liquids containing decreasing quantities of the agent to be removed. It is not, however, necessary completely to remove such relatively non-volatile solvents as may remain in the materials after spinning. In fact, the feel and appearance of the materials may be improved by allowing a certain proportion of such solvents to remain therein. This proportion should not, however, be so great as substantially to decrease the strength of the filaments. The retention of a certain proportion of the solvent may have an important effect upon the behaviour of the materials towards delustring agents. Thus materials containing the relatively non-volatile solvents are found to be in general more readily delustrable by the action of hot or boiling aqueaosiue ous media than are similar materials which dd not contain relatively non-volatile solvents. On the other hand, by subjecting materials con-' taining such solvents to the action of substan-j tially dry steam, for example by the process of British Patent No. 332,187, the materials may be rendered more resistant to delustring than similar materials free from solvent, and may in fact be rendered entirely resistant to delustring.

The spinning solution may contain solid or liquid substances in dispersed or finely divided form. Such substances may for example be introduced as described in British Patents Nos. 333,926, 341,897, 343,949, 346,678 and 346,793 in order to modify the lustre of the resulting products.

The percentage of cellulose derivative contained in the spinning solution will naturally depend to some extent upon the nature of the solvent medium, and upon the particular results desired, for example the denier of the materials to be produced. Good results are obtained with spining solutions containing from 15-35% of the cellulose derivative, but higher or lower percentages may be employed. We have obtained the best results with spinning solutions containing approximately 25-30% of the cellulose derivative. When relatively high percentages of cellulose derivative are employed, spinning may be facilitated by reducing the viscosity of the solution by suitable means, for example by the addition to the solution of electrolytes or the like, as described in British Patent No. 366,110 or byspinning at a temperature above atmospheric, see U. S. Patent No. 1,997,632.

The invention permits of the application of a relatively high draw-down or stretch to the materials emerging from the spinning jets or dies, so that Very fine filaments and the like may be obtained.

An additional stretch may if desired be imparted to the materials continuously with their production. Any suitable means may be employed for producing this effect; for example;

the materials may be passed in contact with two or a series of rotating members of successively increasing peripheral speeds; or the stretch may,

be imparted by any swift, bobbin, spinning pot,

or other collecting device, run at a suitable speed, or the principles of U. S. Patent No. 2,027,419 and British Patent No. 375,424 may be applied. Where such-an additional stretch is to be imparted, softening agents may if desired be applied to the; materials by any convenient means; or spinning may be carried out so that the materials retain a suflicient quantity of such agents.

The processes of the invention may be combined with any suitable treating processes de signed, for example to modify the colour, dyeing properties, lustre, feel, strength or other properties of the material.

Fatty or oily bodies may be applied to the materials at any stage in their manufacture. Such substances may be adapted to facilitate subsequent mechanical operations such as weaving or knitting, or may be particularly adapted to impart a soft feel to the materials. Such oily or fatty bodies may, for example be present in the coagulating and/ or after treatment media. They may, according to their solubility or otherwise in'these media, be present in solution, in the form of a dispersion, or even as a separate layer. Thus when aqueousc'oagulating or treating media are employed, water soluble oily or fatty bodies, for example Turkey red oil, and other sulphonated oils of organic ormineral origin may be contained in solution in such baths. On the other hand, insoluble oils and the like may be dispersed throughout the bath, or may float as a layer on the surface thereof.

The following examples illustrate the invention, but they are not to be considered as limiting it in any way:

Example 1 A 27% solution of cellulose acetate in acetone is spun into a bath containing 360 grams of acetic acid, 120 grams of ethyl lactate and 20 grams of sodium acetate per litre. The length of the filaments immersed in the bath is 10". The fila-' ments are drawn off and wound after an air run of 50" at a temperature of 25 C. at a winding speed of 50 metres per minute.

Example 2 A 27% solution of cellulose acetate in acetone is spun as in Example 1, except that the coagulating bath contains 300 grams of acetic acid, 200 grams of ethyl lactate and 100 grams of sodium acetate.

Example 3 A 27% solution of cellulose acetate in acetone is spun into a bath containing '550 grams acetic acid and 90 grams of sodium acetate. The length of the filaments immersed in the bath is 10'. The filaments are drawn off and wound after an air run of 50" at 25 C. at a winding speed of 25 metres per minute.

What we claim and desire to secure by Letters Patent is 1. In a process for the manufacture of artificial materials by wet spinning processes from solutions of cellulose acetate, the step of effecting coagulation by means of coagulating media containing 30- l0% of acetic acid and 10-20% of ethyl lactate.

2. In a process for the manufacture of artificial materials by Wet spinning processes from solutions of cellulose acetate, the steps of effecting coagulation by means of coagulating media containing 30-40% of acetic acid and 10-20% of ethyl lactate, so that the products emerge from the coagulating medium in a state of such plasticity as to be capable of coalescence in the absence of the adhering liquid, applying a stretch to the formed materials to produce products of low denier, and removing excess of solvent.

3. In a process for the manufacture of artificial materials by wet spinning processes from solutions of cellulose acetate, the steps of effecting coagulation by means of coagulating media containing 30-40% of acetic acid and 10-20% of ethyl lactate, so that the products emerge from the coagulating medium in a state of such plasticity as to be capable of coalescence in the absence of the adhering liquid, applying a stretch to the formed materials to produce products of low denier, and passing the materials through the air so as to remove at least in part the excess of solvent.

4. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of organic derivatives of cellulose, the step of efiecting coagulation by means of a coagulating medium containing at least 20% of a lower aliphatic acid containing not more than four carbon atoms which is a swelling agent for the organic derivative of cellulose and at least 10% of a relatively high boiling solvent for the cellulose derivative, the total solvent content of the medium being of the order of 50%.- V

5. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of organic derivatives of cellulose, the steps of efiecting coagulation by means of a coagulating medium containing at least 20% of a lower aliphatic acid containing not more than four carbon atoms which is a swelling agent for the organic derivative of cellulose and at least 10% of a relatively high boiling solvent for thecellulose derivative, the total solvent content of the medium being of the order of 50%, so that the products emerge from the coagulating medium in a state of such plasticity as to. be capable of coalescence in the absence of the-adhering liquid, and removing'excess of solvent from the products. L Y

6. In a process for the manufacture of artificial filaments, threads, yarns-and the like by wet spinning processes from solutions of cellulose acetate, the step of effecting coagulation by means of a coagulating medium containing at least 20% of a lower aliphatic acid containing at most two carbon atoms and at least 10% of a relatively high boiling solvent for the cellulose acetate, the total solvent content of the medium being of the order of 50%.

'7. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet pinning processes from solutions of cellulose acetate, the step of effecting coagulation by means of a coagulating medium containing a high boiling solvent for the cellulose acetate and at least 20% of acetic acid, the total solvent con tent of the medium being of the order of 50%,

8. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of cellulose acetate, the steps of effecting coagulation by means of a coagulating medium containing a high boiling solvent for the cellulose acetate and at least 20% of acetic acid, the total solvent content of the medium being of the order of 50%, so that the products emerge from the coagulating medium in a state of such plasticity so as to be capable of coalescence in the absence of the adhering liquid, applying a stretch to the formed material to produce products of low denier, and removing excess of solvent from the products.

9. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of cellulose acetate, the steps of eflecting coagulation by means of a coagulating medium containing at least 20% of acetic acid and at least 10% of a high boiling solvent for the cellulose acetate, the total solvent content of the medium being of the order of 50%, so that the products emerge from the coagulating medium in a state of such plasticity as to be capable of coalescence in the absence of the adhering liquid, applying a stretch to the formed materials to produce products of low denier and removing excess of solvent from the products by washing them with aqueous liquids containing lower concentrations of the solvent to be removed.

10. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of cellulose acetate, the steps of effecting coagulation by means of a coagulating medium containing 30-40% of acetic acid and 10-20% of glycol mono-acetate, so that the products emerge from the coagulating medium in a state of such plasticity as to be capable of coalescence in the absence of the adhering liquid, applying a stretch to the formed materials to produce products of low denier, and removing excess of solvent from the products.

11. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of organic derivatives of cellulose, the step of eifecting coagulation by means of a coagulating medium containing a soluble salt, a relatively high boiling solvent for the cellulose derivative and at least 20% of a lower aliphatic acid containing not more than four carbon atoms which is a swelling agent for the organic derivative of cellulose, the total solvent content of the medium being of the order of 50%.

12. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of cellulose acetate, the steps of effecting coagulation by means of a coagulating medium containing a soluble salt, at least 10% of a relatively high boiling solvent for the cellulose acetate and at least 20% of acetic. acid, the total solvent content of the medium being of the order of 50%, so that the products emerge from the coagulating medium in a state of such plasticity as to be capable of coalescence in the absence of the adhering liquid, applying a stretch to the formed materials to produce products of low denier and removing excess of solvent from the products.

13. In a process for the manufacture of artificial filaments, threads, yarns and the like by wet spinning processes from solutions of cellulose acetate, the step of effecting coagulation by means of a coagulating medium containing 30-40% of acetic acid, 10-20% of ethyl lactate and a proportion of the order of 10% of sodium acetate.

WILLIAM ALEXANDER DICKIE. PERCY FREDERICK COMBE SOWTER. 

